On Thursday, Congress Party President Sonia Gandhi publicly backed former Prime Minister Manmohan Singh, who has been summoned as an accused in the coal scam case by a special court under the Central Bureau of Investigation.

"We are outraged at news of summons being served to Manmohan Singh. He is being in the world over as the man of integrity, probity. The Congress is fully behind him. We are sure that he will be vindicated," Gandhi said.

A special court under the CBI summoned the former prime minister along with billionaire Kumar Mangalam Birla to appear on April 8. Most coal block awards made by Singh's government, which ran India for a decade, were overturned by the Supreme Court after it ruled the process illegal late last year.

On Thursday, Gandhi led a solidarity march from the Congress Party headquarters on Akbar Road to 3 Motilal Nehru Marg, Singh's house. “We are here to show our solidarity.. we shall fight it legally," she said. “We are here at the news of summon being served to the former prime minister Manmohan Singh…. He is known not just in our country but also in other countries for his integrity and probity."

Singh said he was "more than pleased and grateful" about his party's support. "The Congress party, Soniaji and all members of the working committee and senior leaders have come to my residence, expressed solidarity with me and that we will fight this case to the best of our ability," he said, PTI reported.

Six accused have been summoned on April 8 for the alleged offences punishable under Sections 120B (criminal conspiracy) and 409 (criminal breach of trust by public servant, or by banker, merchant or agent) of the IPC and under the provisions of the Prevention of Corruption Act (PCA).

"Of course, I am upset but this is part of life. I have always said I am open for legal scrutiny...I am sure the truth will prevail and I will get a chance to put forward my case with all the facts," Singh said on Wednesday.

On Thursday, Congress workers also took out rallies and stopped trains at several stations across Uttar Pradesh to protest against Singh being summoned by the CBI court. ANI reported that Uttar Pradesh Congress Party chief Rita Bahuguna Joshi led Congress workers into stopping the Howrah-Amritsar Express at Lucknow's Charbagh railway station for over an hour.

Senior Congress leaders have also spoken out in support Singh. "The whole world is aware of the personal integrity and honesty of Dr Manmohan Singh. We respect the judicial system. This case has been a misstep," former Finance Minister P Chidambaram said, IBN-Live reported.